Bee It Know: Biodiversity is essential to ecosystems

A study conducted by Rutgers on bees shows how different species pollinate the same plants over time

Rutgers has conducted the first study showing how many additional bee species are needed to maintain crop yields when a longer term period is considered.

In the paper, which was recently published in Nature Ecology & Evolution, the scientists said the biodiversity of the bee population is essential for maintaining the ecosystem function of crop pollination, which is essential for food supply. food for mankind.

“We found that biodiversity plays a key role in the stability of ecosystems over time,” said Natalie Lemanski, the study’s lead author and a postdoctoral fellow in the Department of Ecology, Evolution and Natural Resources at the Rutgers School of Environmental and Biological Sciences. (SEBS). “You actually need more bee species to get stable pollination services over a growing season and over years.”

The study team focused on diverse bee populations on dozens of farms in New Jersey, Pennsylvania and California and found that many more bee species were not only needed for pollination than expected over an entire flowering season, but even more was needed over several years.

The researchers said they found that different species of bees pollinate the same types of plants at different times of the year. They also found that different bee species were the dominant pollinators on the same type of plants in different years. Due to natural fluctuations in bee populations, the researchers said, all bee species present were needed to maintain a minimum threshold of pollination during lean years.

“This research shows that the abundance [of a species] matters, but bee diversity matters even more,” said Michelle Elekonich, deputy director of the National Science Foundation’s Biological Sciences Branch Division, which funded the study. “It’s not the same bees that are abundant at any given time, and variety is needed to maintain balance over a growing season – and from year to year.”

Lemanski said the study offers justification for a long-held concept that environmentalists call the “insurance hypothesis.” The idea is that ecosystems likely benefit when nature “diversifies the portfolio,” supporting multiple species of a class of plant or animal, rather than relying on one dominant species.

“We found that two to three times more bee species were needed to achieve a target level of crop pollination during a growing season compared to a single date,” Lemanski said. “Similarly, twice as many species were needed to ensure pollination over a six-year period compared to a single year.”

The researchers based their analysis on their own extensive observations of bee visits to flowers and measurements of the amount of pollen grains deposited on individual flowers over weeks and months in a given calendar year. , then over several years. They collected the data, with farmers’ permission, from 16 blueberry farms in southern Jersey, 25 watermelon farms in central Jersey and eastern Pennsylvania, and 36 watermelon farms in the Central Valley of the northern California.

“The magnitude of increase in needed species over multiple years was remarkably consistent across cropping systems when considered over the same time interval,” Lemanski said. “Furthermore, the fact that the relationship between the time scale and the number of species needed has not stabilized suggests that even longer time series, spanning multiple seasons, may further reinforce the need for biodiversity to ensure a reliable ecosystem service.”

Rachael Winfree, a professor in the Rutgers Department of Ecology, Evolution and Natural Resources at SEBS, was lead author on the paper, which was also co-authored with Neal Williams of the University of California-Davis. Funding was provided by the National Science Foundation (NSF) and the United States Department of Agriculture, National Institute of Food and Agriculture, Agriculture and Food Research Initiative.

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